Great question. While we agree you could get more in returns from 3x 580's on Eth and ZCash, the P102 does much better on Nist, Lyra, PI1612 and X16R based algorithms. Off that as well, the 3x you mentioned would be doing ~420-450 watts which is 68-80% more power. Crank this up to anything over 20 cards and the P102 scales much better.

Regardless, this case is one where our mining report could help you out even though our cards don't fit into your mining profile. Thanks for the comment!